1. Field of the Invention
The present invention relates to a joint for piping, and in particular, to a joint for piping which is used for piping for a resin tube, a metal tube, or the like, which has relatively small diameter and thickness, used as a supply pipe for refueling or air supply to various vehicles and machines.
2. Related Background Art
Conventionally, as this type of joint for piping, for example, there is known a joint for piping shown in FIG. 13 (see JP-A-9-280451). This joint for piping includes a pipe P, a connector body 1, and a socket body 2. A flow-through hole 24 is formed in an axial position in the connector body 1. An expanding diameter chamber 23 consisting of a small diameter chamber, in which sealing members 26 are contained, and a large diameter chamber communicating with the small diameter chamber is formed in an axial direction thereof in communication with this flow-through hole 24. Engagement holes 29 are provided in position opposed to each other on a peripheral surface thereof.
The socket body 2 includes an annular wall 55 and a projected wall 55′ at an end thereof, and two engagement sections facing outward in a radial direction thereof and two locking pieces 25 facing inward in the radial direction, which are integrally formed extending in the axial direction from the annular wall 55. The socket body 2 is provided inside the connector body 1. In addition, the engagement sections 28 of the socket body 2 engages with the engagement holes 29 of the connector body 1, whereby the socket body 2 is held in a fixed position. Further, an annular swelling wall section (annular spool) P′ is formed near one end of the pipe P.
When one end side of such a pipe P is inserted through the connector body 1, the locking pieces 25 are expanded by the annular swelling wall section P′. After the annular swelling wall section P′ has passed, the locking pieces 25 return to an inner side in the radial direction, whereby the locking pieces 25 and an annular bush 27 hold the annular swelling wall section P′ so as to be engageable, and the pipe P is connected to the connector body 1.
In the case of the joint for piping with such a constitution, when the pipe P is inserted through the connector body 1, the annular swelling wall section P′ is held between the locking pieces 25 of the socket body 2 and the annular bush 27, whereby the joint for piping can be mounted to the connector body 1 easily with one touch of fingers.
In addition, there is known a connector including, as shown in FIG. 14, a body 30, which has a hose connecting section 31 at one end side and a pipe inserting section 32 at the other end side, and a clip 40, which clips a pipe body P inserted in a pipe body inserting section 32 onto a body 30 in association with a stopper protrusion P′ thereof, in which a hose 41 and the pipe body P are connected in a communicating state, stop holes are pierced in clip fit sections on an external circumference of the pipe body inserting section 32, the clip 40 is formed with both ends thereof opposed to each other and in a ring shape biased in a reduced diameter state to be expanded to be mountable to the clit fit section, and locking pawls 42, which are inserted in the stop holes to lock the pipe body P in the pipe body inserting section 32, are provided on an internal circumferential surface of a ring shape (see JP-A-8-233181). Note that, in FIG. 14, reference numeral 43 denotes sealing members.
However, since the conventional joint for piping does not include rotation preventing means, which prevents rotation between the pipe and the connector body, between the pipe and the connector body, in particular, when it is used under a vibrated state, moving dislocation in a direction of the rotation may occur to cause abrasion of the sealing members and induce decrease in airtightness.
As a measure to cope with such a problem, for example, JP-A-7-269765 discloses a joint for piping which is provided with friction giving means between a pipe and a connector to prevent movement in a direction of rotation between the pipe and the connector. As this friction giving means, for example, a system for fitting a projection formed on an internal circumferential surface of a connector body in a slit provided at a tip of a pipe, or a system for disposing bushes for friction on an internal circumferential surface of a connector body and an external circumferential surface at a tip of a pipe is used.
In addition, JP-A-2002-276878 discloses a joint for piping which includes rotation preventing means which is provided with a holding section, with which a spool section of a male joint member engages to hold an end of the joint member so as not to come off, in a retainer and prevents rotation relative to a female joint member through cooperation of a pipe flat section of the male joint member and the holding section of the retainer.
However, the system for preventing movement in a direction of rotation between a pipe and a connector with a friction giving means provided between the pipe and the connector (see JP-A-7-269765) has disadvantages in that it is difficult to process a tip of a pipe end and the processing requires significant labor and time. In addition, the rotation preventing means for preventing relative rotation of a male joint member and a female joint member (see JP-A-2002-276878) has a disadvantage in that a space around a connector is required because a member is pushed from its side into the pipe flat section near the spool section inserted in the connector, and if the space is small, workability is low, in particular, if the connector is in a place where it is hard to be seen, confirmation of end of the work becomes uncertain. In addition, the rotation preventing means also has a disadvantage in that the pipe flat section has directionality in a circumferential direction, and if an angle thereof fluctuates, it may be difficult or impossible to insert the member. Further, it also has a disadvantage in that assembly thereof cannot be completed with one touch of fingers and takes time.